Hydraulic cylinder arrangements typically include a piston member coupled to a rod member to form a piston and rod assembly. Various coupling arrangements have been used in the past to couple a piston member to a rod member.
For example, in a standard piston and rod assembly, a rod member is provided having a reduced-diameter threaded end. A piston member is provided having a longitudinal bore therethrough, the longitudinal bore having a diameter slightly larger than the reduced-diameter threaded end of the rod member. The longitudinal bore extends through the piston member from a first longitudinal end of the piston member to a second longitudinal end thereof and, toward the second longitudinal end of the piston member, opens into a wider-diameter counterbore. During assembly of the piston member with the rod member, the reduced-diameter threaded end of the rod member is inserted into the first end of the longitudinal bore of the piston member until the threaded end of the rod member extends into the wider-diameter counterbore of the piston member. A nut is placed within the counterbore of the piston member and tightened onto the threaded end of the rod member to tightly couple the piston member to the rod member.
Another piston and rod assembly is described in U.S. Pat. No. 5,904,440, issued to Sims. The '440 patent discloses a piston and rod assembly including a rod having a reduced-diameter threaded end and having a transverse opening extending through the reduced-diameter threaded end. Also disclosed is a piston having a longitudinal bore therethrough, the longitudinal bore having internal threads therein for engaging the threads on the rod. A transverse opening, intersecting the longitudinal bore, is also provided through the piston. During assembly, the reduced-diameter threaded end of the rod is screwed into the threaded longitudinal bore of the piston until the transverse opening in the rod is aligned with the transverse opening in the piston. A pin, for preventing further rotation of the rod relative the piston, is then seated within the aligned transverse openings of the rod and piston. Since there are no stressed areas on the rod or the piston upon insertion of the pin into the transverse openings, the pin is retained within the transverse openings of the rod and the piston via a retaining seal, which is disposed about the circumference of the piston and which is positioned to cover the transverse opening in the piston.
Prior piston and rod assemblies may rely substantially upon engagement between threaded portions of a piston and rod assembly for coupling a piston member and a rod member together. Reducing or eliminating such reliance may facilitate stronger or otherwise more practical or economical structural configurations than provided with prior coupling arrangements.
The present invention is directed at overcoming one or more disadvantages associated with prior piston and rod assemblies.